【摘要】 模块化多电平变换器(MMC)应用于高压直流输电等大功率场合时,脉宽调制中的正弦脉宽调制和空间矢量脉宽调制(SVPWM)策略由于控制变量的增多会变得十分复杂,特定次谐波消除脉宽调制(SHEPWM)策略也存在动态性能较差的问题。最近电平调制(NLM)简单并且适用于电平数较多的场合,可以使MMC具有良好的输出特性,但在电平数过低时存在误差较大的缺点。此处针对传统的NLM在电平数过低的分布式电网系统中会产生较大谐波的问题,引入遗传算法(GA)优化桥臂投入子模块数量取整函数,实现了电平数的增加及谐波含量的减少。仿真和实验验证了所提方法的有效性。更多还原

【Abstract】 When the modular multilevel converter(MMC) is used in high-power applications such as high-voltage direct current transmission,the sine pulse width modulation and space vector pulse width modulation(SVPWM) strategies in pulse width modulation will become very complex due to the increase of control variables and the selective harmonics elimination pulse width modulation(SHEPWM) strategy also has the problem of poor dynamic performance.Nearest-level modulation(NLM) is simple and suitable for occasions with a large number of levels which can make MMC have good output characteristics,but there are shortcomings of large errors when the number of levels is too low.Aiming at the problem that traditional NLM will produce large harmonics in distributed grid systems with too low level numbers,a genetic algorithm(GA) is introduced to optimize the rounding function of the number of input submodules of the bridge arm,so as to realize the increase of level number and the reduction of harmonic content.Simulations and experiments verify the effectiveness of the proposed method.更多还原